Instrument for indicating the operating time of vehicles and other devices



Dec. 12, 1950 G THORNTOMNORRls 2,533,638

INSTRUMENT FOR INDICATING THE OPERATING TIME 0F VEHICLES AND OTHER DEVICES Filed Aug. 18, 1947 GEORGE THorWYro flf oefls Kine/fer;

Patented Dec. 12, 1950 iNS'rRIiIi/IENT Foe, INnIdAiiNGjnii -6iiiiit- ATING JrIME F VEHICLE-S AND OTHER DEVICES George Thornton-Norris; London; England Apl lieatiidn Animist 18, 1947, Serial N6, 769,112 In Great Britain August 30, 1 946 This invention relates to instruments for indicating the operating time of vehicles" and other devices; Sucl-i= indication is partic'ularly desirable upon an airplane, since the engine, for example, is dire for servicing of one kind or another, or for replacement, after operation for a" total number of hours, such as 101) hours, or 1000 hours. The airplane may be pilbte'd by many different individuals during that time, and while each is required to enter his flying time in the log book, often such entries are quite inaccurate, and in the aggregate deparaby an appreciable percentage, from the actual-'- operating time. Since one purpose of logging the time is to insure periodical servicing, for safetys sake, the inaccuracy oflogging may precipitate dangerous conditions. Likewise, servicing of other aircraft components, as the hydraulic systems, is often done on a time basis, and in similar fashion servicing of automobile engines or automobiles generally, is desirable ona time-and-milea'ge basis. In all such situations it is desirablethat the time be logged automatically, Without attention by the operator, and indicated clearly at'all timesl It is anobject of the invention to provide" atime integrating and indicating instrument which is driven by electricity andis so arranged that it starts reliably Whenever the current supply is connected at the commencement of an integrat ing period, namely at the'instant when the'vehicl' or equivalent starts to operate In this specification'each period when the instrument is integrat ing the operating time of the vehicle or equivalent is'terfned an operating period.

According to the invention an instrument for indicating the operatingtime of a vehicle or other device-comprises time-indicating means; an oscillatory chronometric balance" which drives the time-indicating means,- electrical means for maintaining the balance in oscillation, a main switch which is closed duringthe operating period for rendering the maintaining means operative;- and a starting device for settingthe balance m oscillation as" said control switch is closed.

There is further provided according to the invention an instrument for indicating" thefoperat irig' time of avehicle or other device, cbm rising time-indicating means; an oscillatory chrono metric balance which drives the time-indicating means, an electromagnet for maintainingthe balance in oscillation, a contact-maker operatedby' the balance'to energis'e the electromagnet'at every" oscillation of the balance;- the contact maker being open when the balance in imperative; 25' nia'in switch which: is 'clesed during the operating 13 Claims. ((31; 161 15) 2 peri 'd fer rendering the maintaining means e'r eand a starting device comprising an aiix ilia-ry switch which is connectedacross the con a emeter; said auxiliary switchbeing closedtempbrariiy to energise the electromagnet and cause the balance to be attracted away from its" KiSlclfiD of rest, thus initiating "eillation.

Gonvenintly the starting device is brought into action at the end of the oneratin bfiod for cheekingthe balance, and thus bringing it rapidly to a standstill. The control switch for the main: tainin' means preferably includesauxiliary contact means which are closedtemporarily during the closing; of said control switch, and if desired daring the opening thereof, so as to bring the' starting means intd actidn.

'I-heinteg'iatingmeans conveniently comprises one; two or more indicators of the cycloineter type having sets of discs or drums nnnibered Ironi- 0 to 9 and arranged to be driven so as to show' a indication df th e number of units of time; say'hour's, during which the vehicle or equivalent has" been operating. If desired one or more of Slili indicators may be provided with re-setting means b yiwhichthey can be readily returned to zero; The indicating inea-n'smay a lso include one o'rfliers angularly' movable hands adapted to be read in cerflunction with a dial,-say to show timessnbrter ene a,- as". minutes. v The invention is illustrated by way of example th acdn ipanying diagrammatic drawings, in WIiiChv Figure 1" is a' front elevation of the preferred form (if instruni for aircraft; together witlrtlie remote fluid-actuated svvitch Figure 2 11s a mi t eievatidfi of theinCheating instrum nt with the from" glass dial-plate and hanu 'rernevd; p

Figure-3 is a rear elevation of the chronornetrie balanee movement shown in Figure 2;

Figure 4- is a sectional elevatiorrtaken on the line of Figure 3;- I Figiire 5 is" aiagrams: the cbntact-riialger scale'y Figure" 6 isa circuit diagrani where a resistance Figure '1 is; an alternative irate diagram in: clii'di h' 1 tapped electrom'agnet (5611-,

aircra t to give an accurate indicatime during the aircraft in operatien; i-. the suin 6f the opera at irig p'ricsdsa It" emirates a cams It fitted with a circular dial-plate ll divided circumferentially at 2 into sixty divisions representing minutes. A radial hand I3 indicates the minutes, and of course moves angularly at the rate of one revolution per hour during the operating periods. To show the number of complete hours two counters l4 and i5 of the well-known cyclometer type are mounted within the casing It so as to be visible through rectangular openings IE and IT in the dial-plate II. A resetting knob It at the bottom of the casing iii is pushed upwards and turned to zeroize the trip counter l4, said knob [8 at the same time turning the hand I3 so that the latter can be left in its upwardly-pointing zero position. The instrument is operated from a battery or other source of electrical energy (not shown) connected to a twin conductor l9 but its action is controlled remotely by a switch unit arranged to be installed at the most convenient position on the aircraft. This unit incorporates a switch which is indicated generally at 2|, and a fluid-pressure capsule 22, which latter is connected by a pipe 23 to a suitable pressure (or vacuum) system which comes into operation when the aircraft is flying; thus the pipe 23 can be connected to the pitot head of the usual air-speed indicator, or to the pressure lubricating system of the engine where the actual engine running time is required to be indicated. A triple conductor 24 is used to connect the unit 2b with the instrument itself.

Internally the instrument comprises an electricaliy driven clock movement 25 of the known form having a chronometric balance wheel 27 (see Figure 3) which is maintained in oscillation by a bar-like iron armature 28 carried by the balance stail 29, said armature swinging through the gap of a G-shaped iron core 3| intermittently energised by an electric coil 32. As mentioned above this form of movement is already known for use in ordinary clocks but its action will be described herein as it is essential for a clear understanding of the present invention. The balance staff 29 is mounted in bearings 33 and 3 5, the latter incorporating the usual regulating pins 35 engaging the spiral balance spring 35; in its static condition the armature 28, which moves as one with the balance wheel 27 is disposed in the inclined position shown in Figure 4 with respect to the pole 3'! of the electromagnet 3!. The supply of current to the coil 32 when the clock movement is running is controlled by a contact-maker device comprising a small thin contact plate 38 which is secured to the balance staff 29 to oscillate therewith and cooperates with a contact pin 39 mounted upon a platform 48 which is electrically insulated from the main parts of the movement, including the balance staif 29. The arrangement of the con tact-maker is shown more clearly in Figure 5. The contact pin 39 is fast upon a triangular plate 4! which is mounted rotatably on a fixed pivot 42, thus holding the pin 39 in the vertical plane of the axis of the staff 29 but allowing it to swing in said plane. The pin 39 is resiliently centered by a light cantilever spring 43 which is anchored to the platform 483 at A l and presses against two spaced pegs 45 and 45 upstanding from the plate. The contact plate 38 is somewhat D-shaped or eccentric and its outwardly projecting part is arranged obliquely as shown diagrammatically in Figure 5; on its back it is covered with electrical insulating material 41. In the static position of the balance staff 29 (shown in Figure 4) the plate 38 is out of engagement with the pin 39.

'magnet remaining dead.

iii

4 As the armature rotates anti-clockwise, as viewed in Figure 4, the part 48 of the plate 38 leads, so that the plate 38 itself engages the contact pin 39, making contact therewith and deflecting it towards the right (as viewed in Figure 5) until the projecting part of the plate 38 passes beyond the pin 39, thus allowing the latter to return to its central position. It will be seen that the electrical contact is made between the pin 39 and plate 38 (and the electromagnet 3| energised) as the armature moves towards the pole-piece 31, but it is broken just before that position is reached, so de-energising the electromagnet and permitting the armature 28 and balance wheel 21 to make their full forward swing. During the return swing the part 49 of the plate 38 leads, so that the pin 39 is deflected leftwards and merc- 1y slides along the insulation 41, the electro- The armature 28 is fitted with a spring pawl 50 (Figure 3) which drives a small ratchet wheel 5i, a spring detent '52 being provided. As shown in Figure 2, the

ratchet wheel 5! drives a central spindle 53 by a reduction gear train 54, 55. The hand 13 is mounted on a sleeve 55 fitted on said spindle and arranged to engage it resiliently, forming a frictional drive which enables the hand l3 to be reset without turning the gear train 54, 55.

The resetting mechanism shown in Figure 2 comprises a bevel gear wheel which is fast upon the sleeve 56 and permanently drives a bevel gear wheel 6i upon the spindle 62 of the trip counter M. This counter is of the type in which reverse rotation of the driving spindle rapidly turns back 5 the indicator wheels until each has reached its zero position. For effecting this operation, the knob I8 is mounted on a spindle 63 which is rotatable and axially slidable in a bearing 64. The spindle 63 is circumferentially grooved at 65 to engage the horizontal arm of a bell-crank lever 66, which arm is normally drawn downwards by a sprin 61. A bevel gear wheel 68 upon the upper end of the spindle 53 is thus held out of engagement with the bevel wheel 60, although it can be brought into engagement and the instrument reset, by raising the knob i8 and then turning it so that the hand l3 moves backwards; after the trip counter M has reached zero, the movement is continued, as necessary, to bring the hand [3 to its vertical zero position. In order to preserve the indication of total hours on the counter 15, the spindle 59 is slidably fitted with a bevel gear wheel Til, the collar of which is circumferentially grooved at H for engagement by the vertical arm of the bell-crank lever 56, so that, as the bevel gear wheel 68 moves into mesh with the central gear wheel 60, the bevel gear wheel Hi moves out of mesh therewith. The spindie 59 is of square or other non-circular shape so as to allow the bevel gear wheel 10 to slide axially and retain its driving engagement with said spindle 69. After resetting, the spring 51 moves the bell-crank lever to bring the gear wheel 10 back into mesh with the central gear wheel 65.

A typical arrangement of the switch 2| and the electrical connections is shown in Figure 6. The switch comprises three mutually insulated contact fingers, namely a central finger 15 which is relatively stiff, and two outer fingers l6, 11 which are resilient. They are mounted upon an anchorage 18 and the upper finger 16 has two contacts I9 and adapted to engage respectively with a contact 81 on the finger I5 to form an auxiliary switch, and a contact 82 on the finger 71 to form a main switch. The finger absence is tends to press the contact is army against the contact at, so that the auxiliary switch 19, 81 is normally closed; the finger ll is actuated by the capsule 22 and normally springs away from the linger 'a'e so that the contacts at, 82 forming the main switches are separated. When pressure fluid is suppliedto the capsule 22 the finger I1 is moved upwards and first closes the main switch by bringing the contact '82 into en eat with the contact at. Ast he upward oi? the capsule 22 increases, the finger It becomes lifted by the Contact 32 and causes disengagement of the contacts '59, 3!; there i how'- ever an a preciame time during which both contacts st and 82 are in engagement with the finger 1e, due mainly to the spring'y nature or the fingers l6 and TL I The 'electr'omagnet coil 32 is connected in series with loading means com rising'a resistance 83, and this is connected to the contact pin 35. The contact plate 33 is connected (by way of the staff 29, balance spring and body of the clock movement Zia) to the finger T6. The finger I! is connected with a master switch 8%, which is conveniently incorporated with the main engine switch or the aircraft, the circuit being fed with current from a battery indicated at 85. A wire 85 leads from the middle finger fifi to thejuncti'o'ri of the (5011 32 with the resistance 8 3 As above mentioned, when the clock movement is static the contact pin 39 is diseneaged fromthe contact plate 38, so that assuming the master switch 84 is closed the mere engagement of the contact 82 with the contact at will not com plete the circuit, and therefore theclock would not start unless the balance were to be set into oscillation by some means. This result is at tain'ed automatically in this device by the middle eontact finger 55. Thus as pressure fluid enters the capsule 22 and causes the lower finger ll to rise, contact is first made at as, ea while con taotsTS, 81 "are still eneaged, so that current can flow through the coil 32 and the wire 8%}, through contacts 8!, l8, thence along fingerlfi to contacts 39, t2 and back to the battery 85; This causes the electromagnet SE to be energised, sothat the armature 28 is attracted and moved sufficiently to bring the contact-maker 38. 39 into action, therefore a current of verv short duration passing through the wire 3% is all that is necessary to start the clock movement; the operating current for said movement is of course fed through the contactsiiil, 82 and. circuit-maker 33, 39 so long as the master switch 813 is closed and the capsule 22 is expanded by pressure fluid. In

order to produce energetic and reliable starting the coil 32 a designed to run normally in series with the loading resistance as, which latter is bypassed by the wire during the initial impulse, thus causing the first momentary current through the coil 32 to be substantially greater than the normal operatina current. If desired a similar result may be obtained by using the arrangement shown in Figure 7 where the resistance 83 is omitted and the wire 35 is taken to a tapping in the coil 32; thus when only part of the coil 32 is in action during the initial starting impulse the circuit impedan e is redu'ced, with the result that a much heavier current cow and produces a stronger energisation of the electroma'gne't 3!. The bypassed portion 3zd of the coil constitutes the loading means in this case, serving to reduce the operating current to its normal value.

It will be noted that when the pressure in the capsulez falls at the-end ofeach operating period, the auxiliary switch '19, trusses a short time before the main switch 80, -62 opens, thus causing the wire '86 to bypass the contact-maker 38, '39. This provides a momentary strong enter-'- gisation of the 'electroma'gnet 3i whichdraws the armature 23 to its central positionwith the reg suit that the oscillation of the balance system is completely or largely damped out to bring the movement rapidly to a standstill, and avoid drivingthe ratchet wheel 51 after the operating period has terminated. I

It will be understood that the arrangements described above are given only by way of example and that various modifications may be made to suit requirements. Thus where the instrument isused to integrate and indicate the flying time of an "aircraft the control switch can beppe'rated by a pneumatic capsule or other variableyo'lume device connected with the cur -speed indicator, the variable volume device, if desired, being embodied in the same casing as the indicating means; alternatively the control switch may be actuated by the retraction and extension of the undercarriage which occurs when the aircraft is airborne, or by any other means which gives the necessary movements determining the beginning and the end of each operating period. Where the instrument is used :01: showing the running time of a vehicle or machine a centrifugal or other rotary device maybe used to work the control switch, while suitahle switch actuating means are usually easy to devise where the instrument is required for other purposes. Any supply of electricity can be used, alternating or direct, and in this connection the device is particularly adapted for aircraft and motor vehicle as the usual storage battery supply is most convenient and suitable. It will be apparent that where the instrument is used to show the operating time of engines, jet propulsion units and like mechanisms, the capsule can be connected with the lubricating oil or fuel oil system so as to bring the clock movement into action when the oil pressure exceeds a predetermined yalue.

The invention provides a simple form of instrument for indicating operating time in which the clock movement comes to rest in a position ens suring that the supply circuit is broken, this form of instrument being particularly desirable as the chance of accidental burning-out of the winding (and consequently the fire risk) is substantially eliminated. Nevertheless the instrument is started reliably and instantaneously wholly by electrical means, atthe commencement of each operating period, without needing recourse to shaking or other mechanical device for bringing the balance into action.

What I claim is:

1. An instrument for indicating the operating timeof a vehicle or the like, comprising an electrically operated chronometric device, including an impulse generating switch normally open but closable periodically to repeatedly energize said chronometric device, an indicator driven by said chrpnometric device,-a main switch in circuit with said impulse generating switch, starting means in shunt across said impulse generating switch intermediate the latter and said main switch, means, shiftable between two positions, and operatively connected to the vehicle or the like to be automatically maintained in or shifted to one such position while the vehicle is stopped, and to be automatically shifted to and maintained in the other such position when the vehicle starts.

said shiftable means being operatively connected to said main switch and said starting means to close the main switch upon starting of the vehicle, thereby to initiate energization of the chronometric device and effect initial closure of the impulse generating switch, by way of the starting means, said shiftable means shifting oppositely upon stopping of the vehicle, for reopening of the main switch.

2. An instrument as set forth in claim 1, wherein the starting means comprises an auxiliary switch, and wherein the shiftable means is operatively engageable with the auxiliary switch to automatically open the latter immediately after closure of the main switch and transmission of an initial starting impulse to the chronometric device, and for automatic reclosure of the auxiliary switch upon reopening of the main switch.

3. An instrument as set forth in claim 2, wherein the main switch is biased to open, and the auxiliary switch is biased to close, and including resilient means operatively interconnecting the shiftable means and said two switches to enable closure of the main switch in advance of opening of the auxiliary switch.

4. An instrument as in claim 3, wherein the resilient means is operatively organized and arranged to enable reclosure of the auxiliary switch in advance of reopening of the main switch, upon stopping of the vehicle and consequent shifting of the shiftable means.

5. An instrument as in claim 1, including an impedance in circuit with the main switch and the chronometric device, but by-passed by the shunt connection of the starting device.

6. An instrument as in claim 1, wherein the chronometric device includes a periodically oscillatable balance staff, and the impulse generating switch includes an eccentrically shaped contact plate carried by said staff and conductive at one face and insulated at its other face, and a contact finger fixedly disposed but resiliently mounted to engage first the conductive face and then the insulated face of said contact plate, as the staff oscillates.

7. An instrument as in claim 6, wherein the chronometric device includes an electromagnet in circuit with and energizable at each engagement of the plates conductive face with the contact finger, and a bar armature, biased towards switch-open position, attracted by said electromagnet and carried by the staiT.

8. An instrument as in claim 1, wherein the shiftable means comprises a pressure-sensitive device opcratively connected to a pressure source which is operative only during operation of the vehicle or the like.

9. An engine operating time indicator comprising time indicating means, an oscillatory chronometric balance which drives the time indicating means, an electromagnet for maintaining the balance in operatin, a contact maker which is operated by the balance so as to close once during each oscillation, the contact maker remaining open when the balance is at rest, a source of electric current connected to the electromagnet and the contact maker in series, a' main switch controllin the flow of current from the source through the electromagnet, a pressure capsule connected to the engine and responsive to fluid pressure developed when the engine is running, and an auxiliary switch which is op erated by the pressure capsule and is connected across the contact maker to short-circuit the latter, said auxiliary switch normally being closed but being opened by the capsule when pressure fluid is fed thereto by the running of the engine.

10. An engine operating time indicator comprising time indicating means, an oscillatory chronometric balance which drives the time indicating means, an electromagnet for maintaining the balance in operation, a contact maker which is operated by the balance so as to close once during each oscillation, the contact maker remaining open when the balance is at rest, a source of electric current connected to the electromagnet and the contact maker in series, a main switch in series with the contact maker, an auxiliary switch which is connected across the contact maker and is normally closed to shortcircuit said contact maker, and a fluid-pressure actuated device arranged to open the auxiliary switch when fed with pressure fluid by the running of the engine.

11. An engine operating time indicator comprising time indicating means, an oscillatory chronometric balance which drives the time indicating means, an electromagnet for maintaining the balance in operation, a contact maker which is operated by the balance so as to close once during each oscillation, the contact maker remaining open when the balance is at rest, a source of electric current connected to the electromagnet and the contact maker in series, a pressure capsule connected to the engine and responsive to fluid pressure developed when the engine is running and a switch device comprising two relatively flexible blades extending alongside one another, a relatively rigid blade extending between said flexible blades, a normally open main switch constituted by cooperating contacts upon the two flexible blades, a normally closed auxiliary switch constituted by cooperating contacts upon one flexible blade and the rigid blade. the pressure capsule being connected to the other flexible blade so that when fluid pressure is fed to the capsule due to running of the engine, movement of said capsule first closes the main switch and then opens the auxiliary switch.

12. An engine operating time indicator according to claim 9, having current-reducing means connected in series with the contact maker, said current-reducing means and the contact maker both' being short-circuited by the auxiliary switch when the latter is closed.

13. An engine operating time indicator according to claim 9, comprising a tapped electromagnet winding, the auxiliary switch being connected between the tapping thereof and that pole of the contact maker remote from the electromagnet.

GEORGE THORNTON-NORRIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,162,447 Bristol Nov. 30, 1915 1,557,721 Passamaneck et al. Oct. 20, 1925 2,008,338 Rodanet July 16, 1935 2,084,226 Strahm June 15, 1937 2,294,031 Hobbs et al Aug. 25, 1942 

